Sanitary single-lever mixers of the abovementioned type are obtainable on the market in the most varied configurations. In spite of a multiplicity of production variants in design and in the detailed configuration of the control apparatus, these have one problem in common: in order to be able to fit and service the control apparatus, it is necessary for the receiving compartment containing the control apparatus to be accessible. The upper aperture provided for that purpose in the receiving compartment must be covered in a suitable manner for two reasons. For one thing, this is a requirement from the aesthetic point of view; for another, dirt and water must be prevented from penetrating into the interior of the single-lever mixer. A closing part which is provided with a spherical upper side is therefore put on above the aperture in the receiving compartment. Either the adjusting lever or the handle must pass through said closing part, for which reason the latter possesses a central through-aperture.
In order to enable the adjusting lever or the handle to perform the movements required when adjusting the control element, this central through-aperture must not be too small. A further measure is therefore required, as a result of which the through-aperture in the closing part, which aperture is already somewhat smaller—compared with the upper aperture in the receiving compartment—is covered in turn. This takes place with the aid of a covering part which is connected to the handle and which slides, with its spherical underside, on the upper side of the closing part. Said covering part is so dimensioned that it covers the through-aperture in the closing part in all the positions of the handle.
Since it is not possible to obtain ideal, play-free sliding of the covering part, which is connected to the handle, on the closing part, which is associated with the housing, and extremely small particles are able to penetrate, over and over again, into the gap between these two elements, in the case of the known single-lever mixers it is not possible, in the long term, to prevent those regions on the upper side of the closing part which are, at times, masked by the covering part and, at other times, left clear by said covering part, from being scratched or becoming unsightly in some other way.
For this reason WO 89/00275 A1, which likewise describes a sanitary single-lever mixer of the generic type, proposes that the closing part associated with the housing be concealed, once again, under a visible cap. This is naturally relatively expensive.
The present invention is directed to addressing these and other matters.